Maternal and child nutrition: effects on health and development throughout the life course Christine P. Stewart, MPH, PhD September 2012
Outline Nutrition and epidemiologic transition Nutrition in pregnancy Barker hypothesis and the fetal origins of disease Life course approach to nutritional epidemiology Selected example: Obesity and diabetes during pregnancy
Background Deficiencies during pregnancy or early childhood have been associated with an increased risk of mortality, morbidity, poor growth, and poor cognitive performance. Overweight, obesity and associated co-morbidities are growing in prominence in many parts of the world The consequences of obesity in pregnancy have only recently begun to be studied
processing Pattern-3: Receding famine The Nutrition Transition Urbanization, economic growth, technological changes for work, leisure, and food Pattern-4: Degenerative disease Pattern-5: Behavior change Starchy, low variety, low fat, high fiber foods Labor-intensive work/leisure Increased fat, sugar, processed foods Shift in technology of work and leisure Reduced fat, increased fruits/veg, fiber Purposeful change in recreation & leisure activities MCH deficiencies, stunting Slow mortality decline Adapted from Caballero & Popkin, 2002 Obesity emerges, bone density prob. Altered life expectancy, NR-NCD body fatness, bone health Healthy aging, NR-NCD
Obesity Trends* Among U.S. Adults BRFSS, 1985 (*BMI 30, or ~ 30 lbs. overweight for 5 4 person) No Data <10% 10% 14%
Obesity Trends* Among U.S. Adults BRFSS, 2010 (*BMI 30, or ~ 30 lbs. overweight for 5 4 person) No Data <10% 10% 14% 15% 19% 20%-24% 25%-29% 30%
While the United States is an extreme example, populations globally are undergoing dramatic transitions in health and nutrition patterns Individuals within those populations are undergoing dramatic transitions in diet, environmental exposures, and disease risk within their own lifetimes
Epidemiologic Transition : Changes in leading causes of death over the past century Figure 1-2 Ten leading causes of death in the United States, 1900 and 2004. Although the definitions of the diseases in this figure are not exactly comparable in 1900 and 2004, the bars in the graphs are color coded to show chronic diseases (salmon), infectious diseases (purple), injuries (aqua), and diseases of aging (white). (Redrawn from Grove RD, Hetzel AM: Vital Statistics Rates of the United States, 1940-1960. Washington, DC, US Government Printing Office, 1968; and National Center for Health Statistics: National Vital Statistics Report, vol 54, no 19, June 28, 2006.)
NUTRITION IN PREGNANCY
Nutrient metabolism Fetus receives nutrient supply from across the placenta via either active transport or facilitated diffusion Changes in nutrient metabolism in pregnancy are driven by: Hormonal changes Fetal demands Maternal nutrient supply
Nutrient metabolism Types of adjustment Accretion of new tissues or deposition in maternal stores Redistribution among tissues Increased turnover or rate of metabolism Increased efficiency of nutrient absorption
Nutrient metabolism Fasting and postprandial glucose levels increase to delivery glucose needed for fetal growth. Elevated hormone levels increase insulin resistance, peaks in 3 rd trimester.
Physiologic changes related to pregnancy Gastrointestinal function Reduced intestinal motility, which leads to increased gastric emptying time (increased heartburn and constipation) Decreased smooth muscle tone resulting in increased water absorption Increased intestinal absorption of nutrients such as iron, calcium and vitamin B12 Increased colonic absorption of water and sodium
Physiologic changes related to pregnancy Renal function Renal plasma flow increases by 50-80% Glomerular filtration rate increases by 50% Increased urinary excretion of glucose, amino acids, and other nutrients Sodium and water retention increases
Physiologic changes related to pregnancy Cardiovascular function Increased cardiac output (amount of blood pumped per beat per minute) Expansion of blood volume ~43% increase in plasma volume ~30% increase in number of blood cells (expansion of the red blood cell mass)
Changes in food intake during pregnancy Some factors explaining changes in food intake: Morning sickness/ food aversions Cravings Taboos, food beliefs Changes in taste acuity (ex. salt) Nutritional counseling
Nutrient requirements of pregnancy Nutrient requirements increase with pregnancy, but not proportionally Maternal behavioral changes augment physiologic changes to meet nutrient requirements A limit exists to the physiologic capacity to adjust metabolism. When that limit is exceeded, fetal growth & development are impaired
LONG-TERM CONSEQUENCES OF UNDER- AND OVER-NUTRITION DURING PREGNANCY
Developmental origins of health and disease hypothesis Early life nutritional and environmental factors may impact later life disease risk Earlier research focused predominantly on fetal growth restriction (indicated by lower birth weight) and adult chronic disease risk
Barker s Hypothesis Infant mortality rates, 1901-1910 CHD mortality rates, 1968-1978 Barker, Mothers, babies and health in later life, 1998
Odds ratios for impaired glucose tolerance or Type II diabetes among 64 yr old men in Hertfordshire (adjusted for adult BMI) Odds ratios for metabolic syndrome among men in Hertfordshire (adjusted for adult BMI) Hales & Barker, 2001
D.S. Fernandez-Twinn, S.E. Ozanne, Physiology & Behavior Volume 88, Issue 3 2006 234-243
The Dutch Famine Late 1944-May 1945 Food supplies in the northern and western regions of the Netherlands were halted due to a German blockade A harsh winter froze the canals, effectively cutting off the vital supply routes Food rations dropped to 500 calories per day 18,000 people died due to starvation during the famine The Dutch Hunger Winter of 1944
Dutch Famine Summary of findings in 50 year old survivors Exposed in early gestation Higher BMI & waist circumference (among women) (Ravelli 1999) Higher ratio of LDL to HDL cholesterol (Roseboom 2000) Increased risk of CVD (OR=3.0) (Roseboom 2000), though findings have been mixed (Lumey 2012) Lower selective attention span in late adulthood (de Rooij 2010) Those exposed during mid- or late gestation had: Born small and stayed small throughout their lives Reduced glucose tolerance (Ravelli 1998) Those exposed in mid-gestation had: Increased risk of microalbuminuria (OR=3.2) (Painter 2005) Increased risk of obstructive airways disease (OR=1.7) (Lopuhaa 2000)
Epigenetics We certainly need to remember that between genotype and phenotype, and connecting them to each other, there lies a whole complex of developmental processes. E.H. Waddington, 1942
Epigenetics DNA methylation Histone modification Non-coding RNAs Zeisel, 2012
The fetal origins of disease Animal evidence has been fairly strong and consistent: Global nutrient restriction, restriction in methyl-donor nutrients (folate, B6, B12, choline), some minerals (Zn, Mg) has adverse effects on cardiovascular development, renal development, insulin signaling, body composition Effects are exacerbated when exposed to a high fat or western diet postnatally
The fetal origins of disease Human evidence has been mixed Long duration of time needed for follow-up contributes to selection bias Large losses to follow-up Survivor bias Confounding by socioeconomic factors, other environmental exposures Difficulty to disentangle prenatal from postnatal effects Difficulty in determining metabolic pathways when insult may have occurred decades prior
Evolutions in epidemiologic thinking The field of epidemiology developed predominantly as a study of infectious disease epidemics Over time, there has been a transition from infectious disease to chronic disease as the primary cause of morbidity and mortality in many countries. Resulting need for new ways of thinking to understand disease causality. More recently, investigators have taken a life course approach to study a variety of health and disease outcomes related to both under- and over-nutrition (among other exposures) during fetal development and beyond.
Differences in ways of thinking about disease causality How long would you have to wait to see an outcome? Exposure to flu virus Incident flu symptoms vs. Poor diet Diabetes
What causes disease? Adult risk factors Does each factor independently cause CVD? Smoking Excessive alcohol Low physical activity Cardiovascular disease Poor diet
What causes disease? Adult risk factors Do you need a combination of risk factors to cause CVD? Smoking + Excessive alcohol + Low physical activity + Poor diet Cardiovascular disease
What causes disease? Factors in childhood Are there critical periods of life in which you are most sensitive to risk? Lung function Kuh & Ben-Shlomo, 2007
What causes disease? Factors in fetal development and infancy Are there critical periods of life in which you are most sensitive to risk? Brain development Grantham-McGregor, 2007
Critical periods of human development Adapted from Moore, The Developing Human, 3 rd ed 1982
CONSEQUENCES OF OVERWEIGHT/OBESITY AND COMPLICATIONS DUE TO DIABETES DURING PREGNANCY
Weight gain recommendations Pre-pregnancy BMI BMI (kg/m 2 ) Total weight gain range Rates of weight gain in 2 nd & 3 rd trimester (mean range in lbs/wk) Underweight <18.5 28-40 1 (1-1.3) Normal weight 18.5-24.9 25-35 1 (0.8-1) Overweight 25.0-29.9 15-25 0.6 (0.5-0.7) Obese (includes all classes) 30.0 11-20 0.5 (0.4-0.6) IOM, 2009
Recommended weight gain for normal weight and obese mothers IOM, 2009
Recommendations vs. reality IOM, 2009
Prevalence of childhood overweight at 7 y by maternal pre-pregnancy BMI categories and gestational weight gain categories. Wrotniak B H et al. Am J Clin Nutr 2008;87:1818-1824 2008 by American Society for Nutrition
Diabetes during pregnancy Infants of diabetic mothers are at significantly greater risk of spontaneous abortion, stillbirth, congenital malformations, morbidity and mortality 3-10% of pregnancies in the United States are affected by abnormal glycemic control, 80% of these are gestational diabetes (GDM) GDM is strongly associated with obesity (Chu, 2007): Overweight women: 2.1 fold greater risk Obese women: 3.6 fold greater risk Morbidly obese women: 8.6 fold greater risk
Diabetes during pregnancy Fetus is exposed to hyperglycemia, resulting in increased fetal insulin levels that serves as a growth promoter and storage of excess energy as fat Fetal macrosomia may result
Mean BMI in siblings exposed and unexposed to a diabetic intrauterine environment Dabelea et al, 2000
Fraser et al, 2012
Risk of diabetes in offspring of diabetic mothers (Pima Indians) Glucose intolerance Prevalence of Diabetes
Fetal hyperinsulinemia Fetal hyperinsulinemia in response to maternal hyperglycemia is a strong predictor of impaired glucose tolerance in later life In animal models, fetal hyperinsulinemia elevates expression of neuropeptide Y (NPY) in the hypothalamus that results in hyperphagia and weight gain in postnatal life
Diabetes during pregnancy: Iron metabolism Uncontrolled glycemia during pregnancy can result in fetal hypoxemia The fetus responds by increasing oxygen carrying capacity of the red blood cell mass. With RBC mass expansion of up to 30%, fetal iron demands are greatly increased Placenta up-regulates iron transport, but cannot fully compensate for higher requirements The fetus draws down fetal liver iron stores 55% reduction in heart iron 40% reduction in brain iron
Diabetes during pregnancy: cognitive impairments Reduced performance on tests of general development in infancy and toddlerhood (deregnier et al 2000) Modest reduction in performance on learning and memory tasks in 3.5 y old children (Riggins et al 2009) Reduced school performance, educational attainment, and IQ (Fraser et al 2012) Impairments are generally mild to moderate, so may be possible to compensate with targeted interventions
Conclusions Nutrition during fetal development can have a lifelong impact on health and disease risk Understanding the consequences of nutritional deficiencies or excesses in pregnancy requires a lifecourse approach, an understanding of the physiology of pregnancy, and of biologic critical windows of development